Lindberg
vacuum pump



July 6, 1965 P. G. LINDBERG VACUUM PUMP 3 Sheets-Sheet 1 Filed June 11, 1959 INVENTOR. PAUL G. LINDBERG ATT RNEYS July 6, 1965 Filed June 11, 1959 P. G. LlNDBERG VACUUM PUMP 3 Sheets-Sheet 2 5o 44 3O 32 32 88 12 I8 60 66 35 62 i 28 6 s4 52 86 4a 46 82 INVENTOR. PAUL e. LINDBERG ATTORNEYS July 6, 1965 P. e. LINDBERG 3,193,190

VACUUM PUMP Filed June 11, 1959 3 Sheets-Sheet 5 so 34 28a 35a.

INVENTOR. PAUL G. L/NDBERG mi M ATTO EYS United States Patent 3,193,199 VACUUM PUMP Paul G. Lindberg, Wiilonghby, Ghio, assignon to Randoiph Mfg. (30., Qieveland, Ohio, a corporation of ()hio Filed June 11, 195), Ser. No. 819,7tl3 4 Claims. (Cl. 230-152) This invention relates to rotary vacuum pumps, and more particularly to dry air rotary vacuum pumps for use in operating aircraft gyroscopic instruments and the like.

The rotary type vacuum pump, of the species of which the present invention is an improvement, includes a cylindrical rotor adapted to carry a plurality of vanes or pistons slidably fitted in the body of the rotor and adapted to move radially outwardly from the rotor responsive to centrifugal force and to discharge pressure when the rotor is rotated at a high speed. The rotor is eccentrically mounted within a stator member and the vanes of the rotor are guided by the interior surface of the cylindrical stator which, due to its eccentricity with respect to the rotor, causes the vanes to move radially inwardly and outwardly as the rotor spins about its axis.

In pumps of this character as heretofore proposed, oil from a reservoir is supplied to the pump cylinder stator for the purpose of providing lubrication, and sealing between the rotor and its vanes against the escapement of compressed air from the high pressure side to the low pressure side of the stator. In fact, in order to obtain as perfect a seal as is possible, it is customary to literally flood the stator with oil. Needless to say, the oil tends to contaminate the air being compressed and it is then necessary to employ filtering means to remove the oil from the air before the air is discharged from the pump. It is particularly important that clean air be discharged from a vacuum pump for use on aircraft inasmuch as oil contaminated air being discharged from an aircraft in flight tends to foul that portion of the fuselage which comes in contact with the air. This creates both a sanitation problem and a fire hazard problem.

I am aware that so-called dry air type rotary pumps have been built in which the moving parts including the rotor and vanes are made of self-lubricating materials wherein in theory no oil lubricant is required to keep the pump from over-heating due to heat of friction. For various reasons, however, these dry air pumps have been unsatisfactory, and to my knowledge, have not enjoyed a wide acceptance for application on aircraft. Instead, oil lubricated pumps are still being employed in aircraft applications in association with various means for at least partially filtering oil from the discharge side of the pump. Not only are these filtering means merely par tially eflicient, but the complexity of the pumps required by virtue of oil pumping and filtering means renders them difiicult to service and time consuming in replacement.

It is therefore an object of my invention to provide an improved, vane type, dry air rotary vacuum pump in which the rotor and vanes are made of a self-lubricating material in combination with superior and novel means for operating and air cooling the pump; the provision of means to prevent the seepage of oil or grease from rotor shaft bearings into the pump housing; the provision of self-centering means for the rotor; the provision of a stator which is mounted concentric with its rotor; the provision of a novel and improved self-contained package service unit which may be quickly removed from the pump housing and a new unit quickly replaced; the provision of a novel relationship between a stator sleeve and a rotor wherein the stator sleeve is cylindrical in part and elliptical in part to provide superior co-action with 3,l3,i% Patented Juiy 6, 1%65 the rotor, and which is spaced radially from the pump housing to enable air cooling therebetween in an improved manner; and the provision of a single stage dry air rotary vacuum pump having dual compression means in combination and co-acting between the pump rotor and the pump stator to improve the pump capacity over known prior art pumps of the same category.

To the accomplishment of the foregoing and related ends, the invention then comprises means hereinafter fully described and particularly pointed out in the claims, the annexed drawings, and the following description setting forth in detail certain structure embodying the invention, such disclosed means constituting, however, but one of various forms in which the principle of the invention may be employed.

FIGURE 1 is an exploded perspective view of a preferred embodiment of the invention showing the various component parts in axial relationship with each other;

FiGURE 2 is an elevational view of the embodiment of the invention shown in FIGURE 1 and with all parts in their proper assembled position;

FIGURE 3 is a sectional view taken on the line 3-3 of FIGURE 2;

FiGURE' 4 is a sectional view of an embodiment of the invention taken on the line 4-4 of FIGURE 3;

FIGURE 5 is a perspective exploded view of the rotor, vanes and rotor shaft;

FEGURE 6 is a sectional view substantially taken on the line 6-6 of FIGURE 5; and,

FIGURE 7 is a partially sectioned view taken on the line 77 of FIGURE 6.

Reference will now be made to the drawings in greater detail, and in particular to FIGURE 1. A preferred embodiment of my rotary vane-type vacuum pump A includes a housing 12 having an inlet or low pressure port 14 and an outlet or high pressure port 16. A sleeve member 18 is provided with annular flange portions 20 and 22 positioned at opposite ends of the sleeve member, and a third or intermediate annular flange portion 24 encircling the sleeve at approximately its midpoint as measured along its longitudinal axis. Each annular flange portion is grooved to receive 0 rings 25 therein (see FIGURE 4) for sealed engagement with the inner surface as of housing 1.2. A cylindrical rotor 28 is provided with a plurality of equi-spaced axially aligned slots 39 intersecting the periphery of the cylinder. These slots 36 are adapted to receive vane members 32 therein for sliding engagement. The rotor is provided with an axial bore 34 for mounting on a rotor shaft 35, and the axial bore is further provided with a key slot 35 to render the rotor non-rotatable on its shaft, all of the foregoing of which is common practice.

The rotor 28 is adapted to fit within sleeve member 18, as will be described more fully hereinafter, and end plates 38 and 4t? are provided to be fastened to the opposite ends of the sleeve 13 to form end seals and retain the rotor within the sleeve. As will also be described more fully hereinafter, the subcombination designated in FIGURE 1 by the letter B and including sleeve 18, rotor 28, vanes 32, and end plates 38 and 40 comprises, when assembled, a self-contained unit which is readily inserted into and is readily removed from housing 12 by merely removing the housing end bell 42 which is adapted to be fastened to the face 44 of housing 12 by standard threaded fasteners 45. Thus, it will be appreciated that should the pump become defective for any reason whatsoever, by removal of housing end bell 42, the entire pump assembly B can be removed from the housing 12 as a single package unit for servicing, and a replacement package unit can be quickly installed in housing 3.2 without further servicing, dismantling, or adhigh pressure exhaust port 50.

justing of parts by merely replacing housing end bell 42.

Referring now to FIGURE 3 which illustrates the embodiment of the invention shown in FIGURE 1 in cross section and assembled within housing 12, it will be noted that intake ports 44 and 46 are provided in sleeve 18 and are diametrically opposed to each other. Also, exhaust or high pressure ports 48 and 50 (shown in phantom) are also provided in sleeve 18 and are diwill be observed, for instance, that portions 54 and 56 of the interior surface of sleeve 18 diametrically opposed to each other are cylindrical in configuration and that the diameter of rotor 28 is such that it is in sliding contact with these surfaces. Accordingly, it follows that with respect to surfaces 54 and 56, the sleeve 18 is concentrically cylindrical about rotor 28 as referred to a common'longitudinal axis 58. It will also be observed that interior sleeve surfaces 60 and 62 are diametrically opposed and displaced 90 from surfaces 54 and 56. Otherwise stated, surface 60 is intermediate surfaces 54 and 56 and contiguous therewith, and surface 62 is intermediate surfaces 54 and 56 remote from surface 60 and contiguous therewith. Whereas surfaces 54 and 56 are concentrically cylindrical with rotor 28, surfaces 66 and 62 are substantially elliptical in cross section to provide compression chambers 64 and 66. Thus, instead of being eccentrically mounted in a cylindrical sleeve as is customary,

rotor 28 is concentrically mounted in sleeve 18 with re spect to surfaces 54 and 56 which provides self-centering bearing surfaces. Furthermore, with the standard eccentric mounting arrangement common in the prior art, the only contact between the rotor and the rotor housing is the tangential line common to both members. It will be readily recognized that the area contact provided by the concentric housing sleeve 18 in the present invention provides for greater sealing area between the sleeve 18 and the rotor 28 than would be the case if mere tangential contact existed. Thus, the possibility of compressed air escaping from the high pressure side of chamber 64 to low pressure side of chamber 66 and conversely, the high pressure side of chamber 66 to the low pressure side of chamber 64 is considerably reduced.

i By way of further explanation, air is admited in ports 44 and 46 simultaneously, and, due to the centrifugal action of vanes 32, the air is compressed. in chamber 64 as it approaches the high pressure exhaust port 48, and the air is compressed in chamber 66 as it is forced toward In each instance, the pressurized air is adjacent the area sealing surfaces 54 and 56 making sliding contact with the rotor 28. Thus,

it will be seen that I have provided a single stage doubleacting vacuum pump wherein, by virtue of the employment of self-lubricating vanes, a self-lubricating rotor, and area sealing contact between the sleeve 18 and the rotor 28 to separate the high pressure and low pressure areas of the pump one from the other, the common resort to oil for lubricating and sealing purposes has been eliminated.

Reference is now made to FIGURES 5, 6, and 7. In order to reduce chattering of vanes 32 as they pass from cylindrical surfaces 54 and 56 to elliptical surfaces 60 and 62 of sleeve 18, pneumatic air cushions are provided at the base of each vane and interconnected in a manner to enable pairs ofvanes to co-act in assisting each other in their reciprocating movement. Thus, pairs of slots 35a and 35b'are milled into shaft 35. Holes 28a are bored in rotor 28 to connect vane slots 36 containing vanes 32a and 3211 with shaft slots 35a. In like manner, holes 2812 are bored in rotor 28- to connect slots 30 of vanes 32c and 32d with slots 35b of shaft 35. Assuming clock-wise rotation of rotor 28 of FIGURE 6, as vane 32a is forced inwardly by the inner wall surface of sleeve 18, the air in bore 28a and slot 35a is compressed to force vane 3212 into pressure contact'with the inner wall surface of sleeve 18. In likemanner, as vane 32c is urged inwardly, the air in the chambers defined by bores 28]: and slots 35b is compressed to urge vane 32d into pressure contact with the inner wall surface of sleeve 18. By iso pressurizing the sliding action of the vanes 32, any tendency for the vanes to chatter or skip as they pass from cylindrical surface to elliptical surface is eliminated by the pressurizing action of the reciprocating air pockets described.

Attention is next redirected to FIGURES 3 and 4 and with particular reference to sleeve member 18 in which porting facilities 44, 46, 48, and 50 are provided in a manner so as to facilitate the dissipation of heat generated by rotation of the rotor 28 in the sleeve 18. Intake port 46 and exhaust port 48 are on opposite sides of cylindrical sleeve surface 56; whereas intake port 44 and exhaust port 5% are on opposite sides of cylindrical sleeve surface 54. The heat developed by pump operation is carried off by circulationof air at a high velocity about the outer periphery of the sleeve. Annular flange members 20 and 24 define a circular passage between the'sleeve 18 and the housing 12 rendered airtight by employment of 0 rings 25 inserted in grooves on the outer peripheries of annular flanges 2d and 24. In like manner, annular flanges 22 and 24 define a circular air passage between sleeve 18- and housing 12 and is likewise sealed by 0' rings 35. By spacing the intake ports 44 and 46 of sleeve 18 diametrically opposite in the circular air passage. 74 of sleeve 18, cool air is drawn through housing intake port 14 to circulate about air passage '74. from where it is intercepted and drawn into ports 44 and 46. A second pair of diametrically opposed ports 48 and 50 are positioned in circular air passage 72 of sleeve 18. Air drawn into intake ports 44 and 46 passes from right to left in sleeve 18, as seen in FIGURE 4, to be forced from chambers 64 and 66 through exhaust ports 48 and 50 into circular air passage 72. In this manner, constant circulation of air is provided about the air passages 72 and 74 to carry off heat generated between the rotor 28 and the sleeve 18. Whereas annular flange members 2%, 22, and 24 provide sealing contact between sleeve 18 and housing 12, end plates 38 and 40 are secured to'opposite ends of sleeve 18 to seal these portions of the sleeve from housing 12. This then provides a complete self-contained unit or module which may be inserted into or removed from the housing 12' without requiring connection or disconnection of miscellaneous fittings and appendages usually associated with rotary type vacuum pumps.

As is best shown in FIGURE 4, rotor shaft 35 is journaled in bearings 78 and 80 contained in suitable recesses 82 and 84 of housing 12 and housing end bell 42 respectively. A'pair of ports 86 and 88 (see FIG- URES 1 and 4) are provided in each sleeve cap 38 and an adjacent the high pressure sides of chambers 64 and 66. Sleeve caps 38 and 40 are spaced away from bearings '78 and 39 to provide passages 81 between the bearings and compression chambers 64 and 66. Passage 81 permits pressure to build up in and about the bearings '78 and 80 whereby grease or oil is prevented from seeping into sleeve 18. v

In summation, I provide an air cooled, self-lubricating, double-acting, single stage vacuum pump in which a partially concentric stator is employed with the rotor instead of the conventional eccentric mounting of the rotor with I respect'to the stator. By providing an air cushion at the base of each vane, pairs of vanes are coupled to co-act for smooth, chatter-free, reciprocating action. Additionally,

I have provided novel porting means whereby the process of receiving and venting air to and from the pump in association with the novel arrangement of intake and exhaust ports provides means for cooling the pump. The concentric stator portions of the pump provide greater areas of contact between the rotor and the stator to enable sealing between the high and low pressure sides of the pump to an extent that, in combination with the air cooling means provided, liquid sealing and lubricating means on the interior of the pump can be dispensed with.

It is contemplated that changes and modifications may be made in the preferred form of the invention disclosed herein without departing from the spirit and scope of the invention as set forth in the appended claims.

I claim:

1. A vane-type dry rotary vacuum pump comprising a cup-shaped housing defining a pump cavity having an open end and a closed end, said housing having a high pressure port and low pressure port, a removable cartridge inserted into said cavity as a unit from the open end thereof, said cartridge including a shaft having one end supported in the closed end of the housing and projecting through and out the open end of the housing, a sleeve surrounding the shaft, a vane carrying rotor mounted on said shaft within the sleeve, end plates mounted on the opposite ends of said sleeve, a portion of the interior surface of said sleeve being cylindrically concentric about said rotor and another portion of the interior surface of the sleeve being elliptical, the extremities of said elliptical surface intersecting said cylindrical surface and being contoured to provide a smooth, gradual transition from the cylindrical to the elliptical portions, said sleeve having a plurality of outwardly extending circumferential flanges adapted to engage the inner wall surface of said housing and define annular passages surrounding the removable cartridge, a low pressure port in said sleeve adjacent one intersection between said cylindrical and elliptical surface to provide communication between the interior of said sleeve and one of said annular passages, a high pressure port in said sleeve adjacent the other intersection between said cylindrical and elliptic-a1 surfaces to provide a communication between the interior of said sleeve and the other of said annular passages, said low pressure port of the housing being in communication with said one annular passage and said high pressure port of the housing being in communication with said other annular passage, and means for removably securing the cartridge Within the pump cavity.

2. A vane-type dry rotary vacuum pump comprising a cup-shaped housing defining a pump cavity having an open end and a closed end, said housing having a high pressure port and a low pressure port, a removable cartridge inserted into said cavity as a unit from the open end thereof, said cartridge including a shaft having one end supported in the closed end of the housing and projecting through and out the open end of the housing, a sleeve surrounding the shaft, a rotor mounted on the shaft and contained within said sleeve, a plurality of vanes slidably fitted in said rotor, end plates secured to the opposite ends of said sleeve to contain said rotor in said sleeve, annular flange means encircling said sleeve and integral therewith adapted to radially space said cartridge from said housing to define a plurality of circumferential air passages therebetween, low pressure port means providing communication between the interior of said sleeve and one of said passages, high pressure port means providing communication between the interior of said sleeve and the other of said passages, low pressure port means in said housing in communication with said one passage, and high pressure port means in said housing in communication with said other passage, whereby air is drawn through said housing low pressure port means to pass into the interior of said sleeve to circulate about said sleeve in said one passage, and air is discharged from said sleeve to pass through said housing high pressure port and to circulate about said sleeve in said other passage, and a housing end bell to contain said cartridge within said housing, whereby said cartridge is easily removable from the cavity by axially extracting the cartridge as a unit from the open end of the housing.

3. A vane-type dry rotary vacuum pump comprising a cup-shaped housing defining a pump cavity having an open end and a closed end, said housing having a high pressure port and a low pressure port, a removable cartridge inserted in said cavity as a unit from the open end thereof, said cartridge including a shaft having one end supported in the closed end of the housing and projecting through and out the open end of the housing, a sleeve surrounding the shaft, a vane carrying rotor mounted on said shaft within the sleeve, end plates mounted on the opposite ends of said sleeve, a portion of the interior surface of said sleeve being cylindrically concentric about said rotor and another portion of the interior surface of the sleeve being elliptical, the extremities of said elliptical surface intersecting said cylindrical surface and being contoured to provide a smooth, gradual transition from the cylindrical to the elliptical portions, said sleeve having a plurality of outwardly extending circumferential flanges adapted to define with the inner wall of said housing, annular passages surrounding the removable cartridge, resilient means disposed between the flanges and inner wall surface of the housing to permit relative radial movement of the cartridge with respect to the housing, a low pressure port in said sleeve adjacent one intersection between said cylindrical and elliptical surface to provide communication between the interior of said sleeve and one of said annular passages, a high pressure port in said sleeve adjacent the other intersection between said cylindrical and elliptical surfaces to provide communication between the interior of said sleeve and the other of said annular passages, said low pressure port of the housing being in communication with said one annular passage and said high pressure port of the housing being in communication with said other annular passage and means for building up fluid pressure exteriorly of the end plates of the cartridge to provide an oil and grease air barrier about the ends of the cartridge and means for removably securing the cartridge within the pump cavity.

4. A vane-type dry rotary vacuum pump comprising a cup-shaped housing defining a pump cavity having an open end and a closed end, said housing having a high pressure port and a low pressure port, a removable cartridge insorted into said cavity as a unit from the open end thereof, said cartridge including a shaft having one end supported in the closed end of the housing and projecting through and out the open end of the housing, a sleeve surrounding the shaft, a rotor mounted on the shaft and contained within said sleeve, a plurality of vanes slidably fitted in said rotor, end plates secured to the opposite ends of said sleeve to contain said rotor in said sleeve, annular flange means encircling said sleeve and integral therewith adapted to radially space said cartridge from said housing to define a plurality of circumferential air passages therebetween, resilient means disposed between the flange means and the inner wall surface of the housing to permit relative radial movement of the cartridge with respect to the housing, low pressure port means providing communication between the interior of said sleeve and one of said passages, high pressure port means providing communication between the interior of said sleeve and the other of said passages, low pressure port means in said housing in communication with said one passage, and high pressure port means in said housing in communication with said other passage whereby air is drawn through said housing porting the free end of said shaft and'to contain said cartridge Within said housing whereby said cartridge is easily removable from the cavity by axially extracting the cartridge as a unit from the open end of the housing.

References Cited by the Examiner UNITED STATES PATENTS Francisco 2 103136 Hoard et a1. 91-138 Read et a1. 1

Baker et a1 103136 Baker et al. 103-136 Baker et a1. 103136. Machlet l03136 Wilson 230-152 Vickers 103136 Kenney et a1. 103-136 Baker et al. 91-8O Hubacker 103136 Jessop 103- 136 Svenson 103--136 Scott 230-152 Lauck 103-216 5 15 2,787,959 4/57 .Jeannin et al. 103.-136 2,808,814. 10/57 Stewart 91- 138 2,818,025 12/57 Hein 103136 2,870,719 1/59 Murray et a1. Q 103+126 5 2,923,248 2/60 Hodgson' 103-426 FOREIGN PATENTS 274,041 10/ 27 Great Britain. 383,033 11/32 Great Britain. 10 754,347 8/56 Great Britain.

' OTHER REFERENCES Dudco Div. of the New York Air Brake Co., Catalog sheets PFF100, Pumps, April 1955 (2 pages). 15 Vickers, Inc., Bulletin M 5108 April 1955 (1 page).

Vickers, Ina, Parts Catalog No. I1695S, J an. '27, 1958, (4 pages). 7 a v Dudco Div. of the New York Air Brake Co., Bulletin No. 10410.1, May 1961, (4 pages). 20 Vickers, 1110., Bulletin M 5113, February 1962, (4

pages).

JOSEPH H. 'BRANSON, JR., Primary Examiner. 

1. A VANE-TYPE DRY ROTARY VACUUM PUMP COMPRISING A CUP-SHAPED HOUSING DEFINING A PUMP CAVITY HAVING AN OPEN END AND A CLOSED END, SAID HOUSING HAVING A HIGH PRESSURE PORT AND LOW PRESSURE PORT, A REMOVABLE CARTRIDGE INSERTED INTO SAID CAVITY AS A UNIT FROM THE OPEN END THEREOF, SAID CARTRIDGE INCLUDING A SHAFT HAVING ONE END SUPPORTED IN THE CLOSED END OF THE HOUSING AND PROJECTING THROUGH SAID OUT THE OPEN END OF THE HOUSING, A SLEEV SURROUNDING THE SHAFT, A VANE CARRYING ROTOR MOUNTED ON SAID SHAFT WITHIN THE SLEEVE, END PLATES MOUNTED ON THE OPPOSITE ENDS OF SAID SLEEVE, A PORTION OF THE INTERIOR SURFACE OF SAID SLEEVE BEING CYLINDRICALLY CONCENTRIC ABOUT SAID ROTOR AND ANOTHER PORTION OF THE INTERIOR SURFACE OF THE SLEEVE BEING ELLIPTICAL, THE EXTREMITIES OF SAID ELLIPTICAL SURFACE INTERSECTING SAID CYLINDRICAL SURFACE AND BEING CONTOURED TO PROVIDE A SMOOTH, GRADUAL TRANSITION FROM THE CYLINDRICAL TO THE ELLIPTICAL PORTIONS, SAID SLEEVE HAVING A PLURALITY OF OUTWARDLY EXTENDING CIRCUMFERENTIAL FLANGES ADAPTED TO ENGAGE THE INNER WALL SURFACE OF SAID HOUSING AND DEFINE ANNULAR PASSAGES SURROUNDING THE REMOVABLE CARTRIDGE, A LOW PRESSURE PORT IN SAID SLEEVE ADJACENT ONE INTERSECTION BETWEEN SAID CYLINDRICAL AND ELLIPTICAL SURFACE TO PROVIDE COMMUNICATION BETWEEN THE INTERIOR OF SAID SLEEVE AND ONE OF SAID ANNULAR PASSAGES, A HAIGH PRESSURE PORT IN SAID SLEEVE ADJACENT THE OTHER INTERSECTION BETWEEN SAID CYLINDRICAL AND ELLIPTICAL SURFACES TO PROVIDE A COMMUNICATION BETWEEN THE INTERIOR OF SAID SLEEVE AND THE OTHER OF SAID ANNULAR PASSAGES, SAID LOW PRESSURE PORT OF THE HOUSING BEING IN COMMUNICATION WITH SAID ONE ANNULAR PASSAGE AND SAID HIGH PRESSURE PORT OF THE HOUSING BEING IN COMMUNICATION WITH SAID OTHER ANNULAR PASSAGE, AND MEANS FOR REMOVABLY SECURING THE CARTRIDGE WITHIN THE PUMP CAVITY. 